Because the data resource is common to all the stations, it is clear that conflicting situations may occur between the stations when data has to be transmitted to or from this resource.
In case there are only two stations, this problem may be solved by using a so-called dual access data resource which has the particularity to be individually linked to each of the stations. A drawback of this solution is that such a dual access resource is expensive.
Another solution, which is also valid when more than two stations are coupled to the common data resource, is to assign to each station a recursive predefined time slot during which a corresponding transmission of data is allowed. A disadvantage of this solution is that, when one or more stations do not require the transmission of data during their allocated time slot, the time then wasted causes the multi-access device to be inefficiently used. Furthermore, two or more stations cannot transmit simultaneously.